This invention relates to improvements in inflatable athletic balls such as soccer balls, volleyballs and basketballs and more particularly, to balls of the inflatable type with remarkably improved touch.
Conventional athletic balls of the inflatable type can be broadly classified into two groups: One group is a so-called "glued panel ball" in which an inflatable tube or bladder to be an innermost layer is reinforced thereon with a winding of thread, yarn or cord, or reinforced by bonding cotton cloth to the outer surface of the tube and after covering the wound or covered tube with an intermediate rubber layer, it is molded and vulcanized, or an adhesive is directly applied to the reinforcing layer to bond with an outer cover. The other group is a so-called "hand sewn ball" in which quadrants of an outer cover stock are disposed on a rubber tube or bladder and then seamed together to surround the tube with the cover without use of an adhesive. The glued panel ball has generally excellent durability but is much poorer in touch or resiliency than the hand sewn ball. So far as volleyballs of the glued panel type are concerned, the ball of a nylon thread winding construction is superior several times in durability, but is poor in touch as compared with the ball of a cotton cloth-reinforcing construction. Since, for volleyballs and footballs, importance is attached to their touch, the glued panel type of balls are frequently shunned by players.
Several improvements in touch of these glued panel types of balls have been already known including an improvement in which the reinforcing layer is constituted of a three-layer construction as disclosed, for example, in Japanese Patent Publication No. Sho 48-40024 and an improvement directed to a reinforced construction by windings of two kinds of threads which are different in modulus of elongation (or modulus of elasticity) as proposed in Japanese Patent Publication No. Sho 52-32292.
However, these two improving methods concerning the touch of the glued panel type of balls are very complicated to fabricate and do not show any remarkable improving effects, and are accordingly not reduced into practice now.
As stated before, the glued panel ball of the thread winding construction has a vital drawback that its touch is poor. Extensive studies have been made to improve this touch characteristic and as a result, it has been found that when a urethane elastomer thread (spandex) or a rubber thread which has never been employed up to now as an elastic thread material of prior-art balls reinforced by thread windings is incorporated in the reinforcing winding layer of the inflatable ball of the reinforcing winding type, an extremely good touch can be imparted to the ball. The present invention is completed based on the above finding.
In fabricating an inflatable ball of the reinforcing winding type, when a urethane elastomer thread or a rubber thread is used in combination with a conventionally employed nylon filament or a polyester filament thread and is wound at random about a ball substrate together with the reinforcing filament, the touch of the ball is pronouncedly improved since the urethane elastomer thread or rubber thread wound at random in the reinforcing winding layer is able to absorb high impact force while keeping the excellent durability of the winding-reinforced construction at a sufficiently high level.